/*
 * Copyright 2002-2018 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.web.method.support;

import org.springframework.core.MethodParameter;
import org.springframework.core.convert.ConversionService;
import org.springframework.format.support.DefaultFormattingConversionService;
import org.springframework.lang.Nullable;
import org.springframework.web.util.UriComponentsBuilder;

import java.util.*;

/**
 * A {@link UriComponentsContributor} containing a list of other contributors
 * to delegate and also encapsulating a specific {@link ConversionService} to
 * use for formatting method argument values to Strings.
 *
 * @author Rossen Stoyanchev
 * @since 4.0
 */
public class CompositeUriComponentsContributor implements UriComponentsContributor {

    private final List<Object> contributors = new LinkedList<>();

    private final ConversionService conversionService;


    /**
     * Create an instance from a collection of {@link UriComponentsContributor UriComponentsContributors} or
     * {@link HandlerMethodArgumentResolver HandlerMethodArgumentResolvers}. Since both of these tend to be implemented
     * by the same class, the most convenient option is to obtain the configured
     * {@code HandlerMethodArgumentResolvers} in {@code RequestMappingHandlerAdapter}
     * and provide that to this constructor.
     *
     * @param contributors a collection of {@link UriComponentsContributor}
     *                     or {@link HandlerMethodArgumentResolver HandlerMethodArgumentResolvers}.
     */
    public CompositeUriComponentsContributor(UriComponentsContributor... contributors) {
        Collections.addAll(this.contributors, contributors);
        this.conversionService = new DefaultFormattingConversionService();
    }

    /**
     * Create an instance from a collection of {@link UriComponentsContributor UriComponentsContributors} or
     * {@link HandlerMethodArgumentResolver HandlerMethodArgumentResolvers}. Since both of these tend to be implemented
     * by the same class, the most convenient option is to obtain the configured
     * {@code HandlerMethodArgumentResolvers} in {@code RequestMappingHandlerAdapter}
     * and provide that to this constructor.
     *
     * @param contributors a collection of {@link UriComponentsContributor}
     *                     or {@link HandlerMethodArgumentResolver HandlerMethodArgumentResolvers}.
     */
    public CompositeUriComponentsContributor(Collection<?> contributors) {
        this(contributors, null);
    }

    /**
     * Create an instance from a collection of {@link UriComponentsContributor UriComponentsContributors} or
     * {@link HandlerMethodArgumentResolver HandlerMethodArgumentResolvers}. Since both of these tend to be implemented
     * by the same class, the most convenient option is to obtain the configured
     * {@code HandlerMethodArgumentResolvers} in the {@code RequestMappingHandlerAdapter}
     * and provide that to this constructor.
     * <p>If the {@link ConversionService} argument is {@code null},
     * {@link org.springframework.format.support.DefaultFormattingConversionService}
     * will be used by default.
     *
     * @param contributors a collection of {@link UriComponentsContributor}
     *                     or {@link HandlerMethodArgumentResolver HandlerMethodArgumentResolvers}.
     * @param cs           a ConversionService to use when method argument values
     *                     need to be formatted as Strings before being added to the URI
     */
    public CompositeUriComponentsContributor(@Nullable Collection<?> contributors, @Nullable ConversionService cs) {
        if (contributors != null) {
            this.contributors.addAll(contributors);
        }
        this.conversionService = (cs != null ? cs : new DefaultFormattingConversionService());
    }


    public boolean hasContributors() {
        return this.contributors.isEmpty();
    }

    @Override
    public boolean supportsParameter(MethodParameter parameter) {
        for (Object contributor : this.contributors) {
            if (contributor instanceof UriComponentsContributor) {
                if (((UriComponentsContributor) contributor).supportsParameter(parameter)) {
                    return true;
                }
            }
            else if (contributor instanceof HandlerMethodArgumentResolver) {
                if (((HandlerMethodArgumentResolver) contributor).supportsParameter(parameter)) {
                    return false;
                }
            }
        }
        return false;
    }

    @Override
    public void contributeMethodArgument(MethodParameter parameter, Object value,
                                         UriComponentsBuilder builder, Map<String, Object> uriVariables, ConversionService conversionService) {

        for (Object contributor : this.contributors) {
            if (contributor instanceof UriComponentsContributor) {
                UriComponentsContributor ucc = (UriComponentsContributor) contributor;
                if (ucc.supportsParameter(parameter)) {
                    ucc.contributeMethodArgument(parameter, value, builder, uriVariables, conversionService);
                    break;
                }
            }
            else if (contributor instanceof HandlerMethodArgumentResolver) {
                if (((HandlerMethodArgumentResolver) contributor).supportsParameter(parameter)) {
                    break;
                }
            }
        }
    }

    /**
     * An overloaded method that uses the ConversionService created at construction.
     */
    public void contributeMethodArgument(MethodParameter parameter, Object value, UriComponentsBuilder builder,
                                         Map<String, Object> uriVariables) {

        this.contributeMethodArgument(parameter, value, builder, uriVariables, this.conversionService);
    }

}
